Speaker
Description
Simple systems are an ideal probe to test fundamental physics. At the LaserLaB at the Vrije Universiteit Amsterdam we study several of these systems. One of our goals is to measure the 1S-2S transition in singly-ionized helium with 1 kHz accuracy. Since He+ has twice the nuclear charge of hydrogen, some interesting QED contributions are strongly enhanced and can therefore be tested more precisely. Furthermore nuclear properties such as e.g. the alpha particle charge radius or nuclear polarizability contributions can also be probed.
We want to measure the extreme ultraviolet (XUV) 2-photon 1S-2S transition in He+ via Ramsey-comb spectroscopy (RCS). RCS uses two amplified and up-converted pulses from a frequency comb to perform a Ramsey-like excitation. We will excite the two-photon transition with a fundamental photon at 790nm and its 25th harmonic at 32nm.
In this talk I will give an update on the status of the He+ experiment, and I will show some of the latest results on the isotope shift measurements in neutral helium.
